The present invention relates to devices for the recording of information, and more particularly, to enclosures for such devices. A typical enclosure for a recording device has a base and a hinged cover. The base houses a printing medium, such as a roll of paper that is wound onto a spool supported by a spindle. A printing device, such as a thermal printhead, is included to record information onto the printing medium. The paper strip is advanced by a roller that is biased against the thermal printhead and that is driven by a motor.
When a replacement roll of paper is placed into a conventional enclosure, the hinged cover is manually swung open to expose the recording device. The existing roll of paper is then manually removed from the base and the spindle pulled from the center of the spool. Next, a replacement roll of paper is inserted over the spindle and placed into the enclosure. The free end of the paper on the roll is then threaded between the thermal printhead and roller by rotating the roller and, finally, the cover is closed.
Conventional enclosures for recording devices perform adequately in many situations. As will be appreciated, however, the replacement of paper in a conventional recording device enclosure is a time-consuming, multistep process. For many applications, such as the enclosure of recording devices used in emergency medical care equipment, this process may be unacceptably slow.
One proposed solution to the problem of multistep paper replacement is offered by U.S. Pat. No. 4,641,980 (Matsumoto), which discloses an enclosure having a thermal printhead attached to a hinged cover. Although the hinged cover may be selectively locked in a closed position, it is spring-biased toward an open position and can be opened by the depression of a locking release mechanism. When a roll of paper is placed in the enclosure, the free end of the paper on the roll is positioned to overlie the printer. By closing the hinged cover, the paper is then captured between the roller and printhead, eliminating the need for threading.
One drawback of the Matsumoto recording device enclosure is its exposure of the thermal printhead, which is typically fragile, to impact with foreign objects during replacement of the paper roll. This exposure results from the printhead's attachment adjacent the projecting end of the hinged cover. The Matsumoto design also requires a substantial amount of free space around the enclosure to accommodate the arcuate movement of the hinged cover as it is swung between the closed and open positions. As a result, the enclosure may be inadequate for recording devices used in close proximity to other equipment. In addition, unintentional opening of the enclosure and interruption of the operation of the recording device can occur if the Matsumoto locking release mechanism is inadvertently depressed.
Although other enclosures for recording devices have been designed to accommodate separation of the roller and thermal printhead during replacement of the paper roll, they also suffer disadvantages. For example, in one arrangement, a drive chain linkage connects the roller to the motor, and this linkage must be disconnected to permit paper replacement. The linkage must then be reconnected and aligned before operation of the recording device can recommence.